Northern river otters were/are an indigenous native species that the cutthroat co-existed with for thousands of yrs. I can show you dozens of small streams from the Bow drainage south to the US border where it was common to catch bull and cutthroat trout 40 yrs ago but now all you will find is hoards of stunted brook trout because the cutts and bulls have been completely expatriated and please don't get me started on rainbows and brown trout. The Alberta strain of westslope cutthroat, Athabascan rainbow and bull trout don't have the thousands of yrs to wait for the "natural" balance to evolve.
Dream all you want about the "Zen Experience" of "Catch and Release" " All Trout Are Equal" fishing but it comes @ a steep cost.